Tension roll housing for cold strip mills



Dec. 9, 1969 H. G. BARGFELDT 3,482,426

TENSION ROLL HOUSING FOR COLD STRIP MILLS Filed May 15, 1967 l IN [1Affomey United States Patent M 3,482,426 TENSION ROLL HOUSING FOR COLDSTRIP MILLS Howard G. Bargfeldt, Hanover Township, Lake County, Ind.,assignor-to United States Steel Corporation, a corporation of DelawareFiled May 15, 1967, Ser. No. 638,240 Int. Cl. B21b 39/08 US. Cl. 72-2053 Claims ABSTRACT OF THE DISCLOSURE A roll stand housing having separateroll mounting windows therein respectively for the work rolls and for atension roll assembly in a cold strip rolling mill, the arrangement ofboth windows in a common housing operating to reduce to a minimum thelength of the strip between said tension roll assembly and the reducingpass of said work rolls.

This invention relates to mills for cold rolling steel strip and isdirected, more particularly, to an improved mounting for tension rollsused either to apply forward or back tension to strip moving through areducing pass between a pair of work rolls. The improvements of theinvention are obtained, more specifically, by reducing the distance overwhich the strip must travel between the reducing pass and the tensionrolls. In a manner to be described the improved tension roll mounting ofthis invention is effected by providing a housing with a roll mountingwindow therein for the tension rolls in addition to the customary windowin which the strip work rolls are mounted.

Tension roll assemblies are commonly employed in cold strip mills forregulating forward or back tension on strip moving through a reducingpass between the work rolls of a roll stand. As shown, for example, inC. E. Moore Patent No. 2,176,094 and in C. J. Klein et al. Patent No.2,287,380, assemblies of this type comprise a vertically spaced pair ofrolls over which the strip is wound in reverse directions so that theportion of the strip momentarily engaged with such rolls has an S-shapedconfiguration. Such assemblies are usually mounted either in separateroll housings spaced from the housing for the strip work rolls or, asshown in the above patents, are supported by brackets secured to thework roll housings. With tension roll mountings of this character, thestrip travels over a considerable distance, usually several feet,between the work roll reducing pass and the point of its engagement withthe tension rolls.

In the operation of cold strip mills with tension roll assemblies andmountings therefor of the type indicated above, the problem ofmaintaining flatness and tension uniformly over the width of the stripmoving to or from the tension rolls has proved troublesome, particularlywhen rolling thinner gauges. In this respect, the strip when stretchedby the pulling action of the tension rolls has a tendency to shrink orneck-in on itself in a transverse direction, and non-uniform tensionover the width of the strip results in the development of longitudinalfolds or wrinkles. In addition, stretch levelling techniques used tocompensate for this frequently cause edge-cracking and strip breakage.

One of the principal objects of this invention, accordingly, is toprovide a rolling mill which will minimize the elongation and transversenecking forces that cause the operating problems referred to above. Inaccordance with the principles of this invention, this is accomplishedby providing a tension roll mounting which reduces the distance betweenthe tension roll assemblies and the mill work rolls and results in amore compact mill.

3,482,426 Patented Dec. 9, 1969 A related and more specific object ofthe invention is to provide in a cold strip mill a roll stand housinghaving separate windows respectively providing for the mounting thereinof the work rolls and the tension roll assemblies, and in which thehorizontal spacing of such windows as well as the distance between thetension rolls and the work rolls is a minimum, to thereby minimize theaction of the elongation and necking forces when the strip is stretchedlongitudinally.

Other objects and advantages of the invention will become apparent fromthe following description.

In the drawings, there is shown a preferred embodiment of the invention.In this drawing:

FIGURE 1 is a side elevational view of a roll stand housing having atension-roll mounting therein constructed in accordance with theprinciples of this invention;

FIGURES 2 and 3 are sectional views taken respectively along the linesIIII and IIIIII of FIGURE 1, FIGURE 3 being drawn to an enlarged scale;and

FIGURES 4, 5 and 6 are perspective views of parts of the mounting forthe tension rolls shown in the preceding figures.

FIGURES 1 and 2 of the drawings show the manner in which the inventionis applied to a 4-high strip mill that includes a pair of work rolls 1and a pair of backup rolls 2. The rolls 1 and 2 are supported by hearingchocks (not shown) in windows 3 between laterally spaced bearing posts 4and 4a of roll housings 5 at opposite sides of the mill. The drive forrotating the rolls 1 and 2 operates them to deliver the strip S througha reducing pass between the work rolls 1 to a tension roll assembly 6.Reduction of the strip thickness is regulated in the usual manner by ascrew-down mechanism (not shown) which controls the size of the rollingpass between the rolls 1. The tension roll assembly 6 comprises avertically spaced pair of rolls 7 over which the strip S is wound inreverse directions so that the portion of the strip engaged with suchrolls has an S-shaped configuration to provide contact with the rolls 7over a maximum area. From the lower roll 7, the strip S travels upwardlyto a tensiometer roll 8 and then horizontally over a deflector roll 9for delivery to a winding reel. The drive for the rolls 7 includes driveshafts 10 that are operated conventionally to maintain the portion 11 ofthe strip between the work rolls 1 and tension rolls 7 under the desiredforward tension, and to deliver the portion of strip 12 extendingbetween the lowermost rolls 7 and the tensiometer roll 8 to a Windingreel under minimum tension.

In accordance with the principles of this invention, the roll housings 5are constructed to provide a mounting therein for the tension rollassembly 6 and in such manner that the upper tension roll 7 ispositioned as close as possible to the rolling pass between the workrolls 1 to thereby reduce the length of the strip 11 between the rolls 1and the tension assembly 6 to a minimum. For this purpose, the posts 412of the roll stand housings 5 at opposite sides of the mill are cast withenlargements 14 having windows 15 therein that provide a removablesupport for the tension rolls 7 in a manner to be described. By formingthe windows 15 in the posts 4a, the

upper tension roll 7 is located closer to the rolling pass between thework rolls 1 than was heretofore possible with the conventional bracketsupports and separate tension roll stands used previously to support thetension The windows are rectangular in shape and extend vertically andparallel to the windows 3 in which the rolls 1 and 2 are supported. Eachof the windows 15 is defined by spaced side Walls 1-6 and spaced endwalls 17. The support for the opposite ends of the rolls 7 in thewindows 15 comprises a pair of bearing blocks 18, each of which has apair of vertically spaced openings 19 in which the journals 20 atopposite ends of the rolls 7 are rotatably supported by bearings 21. Keyblocks 22 and 23 bolted respectively to the upper and lower end walls 17of the windows 15 are formed with key Slots 24 in which keys 25 securedto the blocks 18 are received to hold the rolls 7 against endwisemovement in the windows 15. Movement of the blocks 18 in the windows 15is further restricted by bars 26 and 27 that are attached to the upperand lower ends of the blocks 18. Removable pins 28 extending throughaligned openings 29 in the lower arms 27 and key blocks 23, and capscrews 30 extending through threaded openings 31 in the upper arms 26,key blocks 22 and bearing post 4a hold the blocks in their assembledposition in the windows 15. The mount ing of the bearing blocks 18 inthe windows 15 provides for removal of the rolls 7 with respect to thehousings 5 as a unit when repair or replacement is required. For thispurpose, it is only necessary to remove the pins 28 and screws 30 sothat the blocks 18 can be moved in a sidewise direction to disengage thekeys 25 from the keyways 24. The assembly of the bearing blocks 18 androlls 7 may then be removed as a unit from the housings 5 by endwisemovement through the windows 15.

As best shown in FIGURE 3, the vertical spacing of the arms 26 and 27 isless than the spacing of the adjacent faces 32 of the key plates 22 and23 to provide for free axial movement of the assembly of rolls 7 andblocks 18 to their mounted positions. In addition these dimensionsprovide a space 33 between the arm 26 and key plate 22 which may bevaried by tightening the bolt 30 to adjust the vertical position of thetension roll assembly 6 and thereby the horizontal position of thepassline of the strip portion 11 relative to the working pass betweenthe rolls 1.

The width of the windows 3 is slightly greater than the diameter of thebackup rolls 2, this being necessary in order that the rolls 2 may beremoved axially through the windows 3. Similarly, the windows 15 have awidth which is slightly larger than the diameter of the tension rolls 7to permit their removal and replacement by axial movement through thewindows 15. By reason of the provision of the windows 15 in the housings5, it will be apparent that the maximum length of the strip portion 11need be only slightly greater than the sum of the radii of the backuprolls 2 and the tension rolls 6, plus the thickness of the columns atthe left of the windows 15 as viewed in FIGURES 1 and 2. However, itwill be noted further that the mounting of the rolls 7 that is providedby the key blocks 22 and 23 provides for a further reduction in thelength of the strip portion 11. By reason of the key slots 24 in theblocks 22 and 23, the bearing blocks 18 are moved to the left as viewedin FIGURES 1 and 2 to positions in which they have abutting engagementwith the sidewalls 16 at the left of the windows '15, and in thesepositions the peripheries of the rolls 7 are located beyond the leftside walls 16 and thus closer to the adiacent sidewall 34 of the window3. This arrangementthus further reduces the length of the strip portion11 by at least a portion of the width of the columns 4c.

While the foregoing describes the invention for the mounting of thetension rolls 7 which is provided by the windows 15 of this invention inthe housings 5 reduces the length of the strip portion 11 between thetension rolls 7 and the reducing pass between the work rolls 1. Byreducing the length of the strip portion 11 over which the tensionapplied by the rolls 7 is effective, it will be apparent that theelongation of the strip by such tension is reduced to a minimum and thatthe necking-in and stretching actions that give rise to the formation oflongitudinal folds and edge-cracking are also minimized.

While the foregoing describes the invention for the mounting of atension roll assembly 6 in a window 15 in the column 4a for applyingforward tension to strip moving through the working pass of the rolls 1,it will be understood that the invention may also be used to apply backtension to the strip. For this purpose the bearing post 4b at the leftof the window 3 need only be provided with a window 15 and a tensionroll assembly 6 mounted therein as described above for the bearing post4a. With this modification in mind, it will be apparent that otheradaptations and modifications may be made without departing from thescope of the following claims.

I claim:

1. In a rolling mill of the type having a set of work rolls defining aworking pass for reducing the thickness of steel strip and a set ofvertically spaced tension rolls over which the strip is wound in reversedirections and travels over an S-shaped path for maintaining the stripbetween said work and tension rolls under tension, a roll standcomprising a housing having a pair of horizontally spaced windowstherein, one of said windows providing a mounting for said set of workrolls therein, and means including the other of said windows formounting said set of tension rolls in said housing.

2. The invention defined in claim 1 characterized by said tension rollmounting means comprising a pair of key plates secured to the upper andlower edges of said other windows, each of said plates having a key slotopening in a direction away from said roll pass, bearing blocks forrotatably supporting said tension rolls, said blocks having keys securedthereto and projecting vertically from the upper and lower edges thereoffor engagement in said key slots, said bearing blocks and said tensionrolls being movable toward said Work rolls to shorten the distancetherebetween upon movement of said keys into said key slots, engagementof said keys in said key slots being effective to hold said bearingblocks and tension rolls against endwise movement in said other windows.

3. In a mill for cold rolling steel strip, the combination with a set ofwork rolls defining a working pass for reducing the strip passingtherethrough, and a set of vertically spaced tension rolls over whichthe strip is wound in reverse directions and travels over an S-shapedpath for maintaining the strip between said work and tension rolls undertension, of a roll stand comprising a housing having a first window forsupporting said set of work rolls therein and a second window spacedhorizontally with respect to said first window, and means for mountingsaid set .of tension rolls in said second window.

References Cited UNITED STATES PATENTS 1,467,880 9/ 1923 Roemer 72-2052,137,611 11/1938 Hetler 72-205 2,195,009 3/ 1940 Lessmann et a1 72-2052,287,380 6/ 1942 Klein et al 72-205 3,136,184 6/1964 Wells 72-2053,210,981 10/1965 Sendzimir 72-234 MILTON S. MEHR, Primary Examiner

